Fuel cell systems are increasingly used as a power source in a wide variety of applications. Fuel cell propulsion systems have also been proposed for use in vehicles as a replacement for internal combustion engines. The fuel cells generate electricity that is used to charge batteries and/or to power an electric motor. A solid-polymer-electrolyte fuel cell includes a membrane that is sandwiched between an anode and a cathode, referred to as an MEA or membrane electrode assembly. MEA's are sandwiched between conductive separator plates. To produce electricity through an electrochemical reaction, a fuel, commonly hydrogen (H2), but also either methane (CH4) or methanol (CH3OH), is supplied to the anode and an oxidant, such as oxygen (O2) is supplied to the cathode. The source of the oxygen is commonly air.
One characteristic of PEM fuel cells is that power is often provided at a higher current and a lower voltage than is required by the loads they are connected to. As a result, a power conversion device is incorporated between the load and the fuel cell stack to step up the voltage supplied to the load. Such power conversion devices increase cost, weight and volume of the fuel cell system.